WO2026005064A1 - Transition metal cluster compound, method for producing said compound, photosensitive composition containing said compound, pattern forming method using said composition, substrate, and method for producing substrate - Google Patents

Abstract

Provided are a transition metal cluster compound capable of achieving miniaturization of a circuit pattern, a photosensitive composition containing the same, and so forth.　A transition metal cluster compound according to the present invention is characterized by containing transition metal atoms and carboxylate ligands A each having an alicyclic structure of saturated hydrocarbons. Preferably, the carboxylate ligand A contains an alicyclic structure of saturated hydrocarbons, which has at least one substituent R, the substituent R is an organic group or a halogen atom, and the alicyclic structure has 3-10 carbon atoms.

Description

Transition metal cluster compound, method for producing the compound, photosensitive composition containing the compound, pattern forming method using the composition, substrate, and method for producing the substrate

The present invention relates to a transition metal cluster compound suitable for use in ultra-microlithography processes, such as those used in the manufacture of ultra-LSIs and high-capacity microchips, and other photofabrication processes, a method for producing the compound, a photosensitive composition containing the compound, a pattern formation method using the photosensitive composition, a substrate, and a method for producing the substrate.

2. Description of the Related Art In the manufacturing process of semiconductor devices, fine processing is carried out by lithography using a photoresist composition.
In semiconductor photolithography, circuit patterns become smaller as semiconductor devices become smaller in accordance with Moore's Law, and further miniaturization is desired.

The development of photolithography can be broadly divided into the shift to shorter wavelength light sources in exposure equipment and the accompanying development of new photoresists. Photoresists are required to meet all of the requirements of high resolution, low roughness, and high sensitivity. Conventional resists are photosensitive compositions containing organic polymer-based photoacid generators, and are known as chemically amplified resists. This type of resist promotes a chemical reaction accompanied by the diffusion of acid, but the acid diffusion process can cause line edge roughness (LER), which can result in a decrease in resolution, and is therefore thought to be incompatible with ultra-fine patterns.

In recent years, non-chemically amplified photoresists (hereinafter referred to as metal-containing resists) have been proposed, which are primarily composed of compounds containing metal elements such as Zn and Sn. In metal-containing resists, the metal component itself is the photosensitive substance and functions as the base material. Because they do not involve acid diffusion, they can improve line edge roughness, making them promising next-generation resist materials for forming finer pattern structures. In fact, it has been reported that finer patterns can be formed using next-generation exposure equipment using extreme ultraviolet (EUV) light.
For example, Patent Documents 1 to 6 and Non-Patent Documents 1 to 3 listed below disclose methods of forming resist patterns using extreme ultraviolet rays (EUV light) or electron beams.
Patent Document 6 describes a transition metal cluster compound composed of a transition metal element and a carboxy ligand including an alicyclic structure having a double bond, but does not disclose that when the alicyclic structure is composed of multiple rings, all of the chemical structures of the multiple rings are composed of saturated hydrocarbons.

JP 2015-108781 A Japanese Patent Application Laid-Open No. 2001-072716 Japanese Patent Application Laid-Open No. 2017-173537 JP 2012-185484 A Japanese Patent Application Laid-Open No. 2021-102604 International Publication No. 2024/143204

Minoru Toriumi etc.,Proc.SPIE,9779(2016)97790G Lianjia　Wu　etc.,Proc.SPIE,10957(2019)109570B Neha Thakur etc.,Proc.SPIE,10957(2019)10957D

In photolithography, particularly semiconductor photolithography technology, there is a demand for photosensitive compositions and pattern formation methods that can achieve even finer circuit patterns.

After extensive research, the inventors discovered that compounds with specific structures are suitable for photoresists compatible with ultra-fine patterns.

The object of the present invention is to provide a transition metal cluster compound that can achieve finer circuit patterns, a photosensitive composition containing the compound, a pattern formation method using the photosensitive composition, a substrate having a pattern layer obtained by the pattern formation method, and a method for manufacturing the substrate.

The present invention has the following aspects [1] to [19].

[1] A transition metal cluster compound comprising a transition metal atom and a carboxylate ligand A having an alicyclic structure of a saturated hydrocarbon.

[2]. The transition metal cluster compound according to [1], wherein the carboxylate ligand A comprises an alicyclic structure of a saturated hydrocarbon having at least one substituent R, and the substituent R is an organic group or a halogen atom.

[3] The transition metal cluster compound according to [1] or [2], wherein the alicyclic structure of the carboxylate ligand A has 3 to 10 carbon atoms.

[4]. A transition metal cluster compound according to any one of [1] to [3], wherein the transition metal atoms are composed of 2 to 20 atoms.

[5]. A transition metal cluster compound according to any one of [1] to [4], wherein the transition metal atom is titanium, hafnium, or zirconium.

[6]. The transition metal cluster compound according to any one of [1] to [5], wherein the alicyclic structure of the carboxylate ligand A is a cyclopropane ring, a cyclopentane ring, a cyclobutane ring, a cyclohexane ring, or a norbornane ring.

[7] The transition metal cluster compound according to any one of [ _1] to [6], characterized in that the carbon atom C1 in the alicyclic structure to which the carboxylate group of the carboxylate ligand A is bonded is a tertiary or quaternary carbon atom and is one of the carbon atoms constituting the cyclic structure of the alicyclic structure.

[8]. A transition metal cluster compound according to any one of claims [2] to [7], wherein the substituent R is an organic group having 1 to 10 carbon atoms.

[9] A transition metal cluster compound according to any one of [2] to [8], wherein the organic group is a hydrocarbon group, aromatic group, ester group, sulfonyl group, alkoxy group, amide group, amino group, or carbonyl oxygen group.

[10]. A transition metal cluster compound according to any one of [2] to [9], wherein the structure of the substituent R does not contain an unsaturated hydrocarbon or aromatic group.

[11]. A method for producing a transition metal cluster compound according to any one of [1] to [10], comprising reacting a compound containing a transition metal atom with a carboxylic acid having a carboxylate ligand A structure in a solution.

[12]. A photosensitive composition containing the transition metal cluster compound described in any one of [1] to [10].

[13] The photosensitive composition according to [12], further comprising a solvent.

[14]. The photosensitive composition according to [12] or [13], characterized in that it contains the transition metal cluster compound according to any one of [1] to [10] in a concentration of 50 to 100 mass% of the total solids.

[15]. The photosensitive composition according to any one of [12] to [14], which reacts with actinic radiation having a wavelength of 6 nm or more and 15 nm or less.

[16]. A pattern forming method comprising the steps of applying the photosensitive composition described in any one of [12] to [15] to a substrate, exposing the applied photosensitive composition to actinic radiation, and developing the exposed photosensitive composition.

[17]. The pattern formation method described in [16], wherein the development is carried out using a developer, and the developer is an organic solvent having a solubility parameter (SP value) of 7.5 or more and 11 or less.

[18]. A substrate having a patterned layer obtained by the pattern forming method described in [16] or [17].

[19] A method for manufacturing a substrate in which a pattern layer is formed by the pattern formation method described in [16] or [17].

The transition metal cluster compound of the present invention contains a transition metal atom and a carboxylate ligand A having an alicyclic structure of a saturated hydrocarbon, and is therefore considered to be an excellent semiconductor photoresist material that is relatively easy to produce by organic synthesis and exhibits high sensitivity when exposed to actinic radiation.

Detailed Description of the Invention

The present invention will be described below based on one embodiment, but the present invention is not limited to this embodiment.
In addition, in this specification, there are some descriptions using "~" as a description expression to indicate a numerical range from a lower limit value to an upper limit value of a numerical value, but the numerical range in this description is a numerical range specified as being equal to or greater than the lower limit value and equal to or less than the upper limit value, including the lower limit value itself and the upper limit value itself.

[Transition Metal Cluster Compounds]
A transition metal cluster compound according to one embodiment of the present invention (hereinafter also referred to as the present cluster compound) is a compound that forms a cluster centered around a transition metal atom, and that includes a transition metal atom and a carboxylate ligand A having an alicyclic structure of a saturated hydrocarbon.
The carboxylate ligand A has a carboxylate group bonded to an alicyclic structure. When the alicyclic structure of the saturated hydrocarbon contained in the carboxylate ligand A is composed of multiple six-membered rings, it is preferable that all of the chemical structures of the multiple rings are composed of saturated hydrocarbons. When the alicyclic structure is not a six-membered ring, it is not necessary that all of the chemical structures of the multiple rings are composed of saturated hydrocarbons.

In the present invention, a cluster compound refers to a metal complex molecule having metal atoms and ligands, in which multiple metal atoms are bonded to each other directly or through bridging ligands, and includes compounds having multiple metal atoms in which the metal atoms have metal-metal bonds or are bonded to each other via 1 to 3 atoms.
The cluster compound may contain oxygen and/or hydroxyl groups within the structure of the cluster compound, and preferably may contain μ-oxo ligands (—O—) in which an oxygen atom is coordinated between metals and/or hydroxyl groups (—OH) in which a hydroxyl group is coordinated to a metal.
The carboxylate ligand is a ligand having at least one carboxylate group, and the carboxylate group is a functional group having a chemical structure of -C(=O)O-. In order to more effectively obtain the effects of the present invention, a ligand having only one carboxylate group is preferred.

The transition metal atoms in the cluster compound are preferably composed of 20 or fewer atoms, since this provides high solubility in a developer before exposure to actinic radiation; and are preferably composed of 2 or more atoms, and more preferably 4 to 12 atoms, since this makes it easier to achieve insolubility in a developer after exposure to actinic radiation.

Furthermore, examples of the transition metal atoms include elements from Period 4 or higher and Groups 3 to 12 of the periodic table. Among these, titanium, hafnium, and zirconium are preferred in terms of ease of production by organic synthesis. Two or more types of the transition metal atoms may be used in combination.

The present cluster compound contains a carboxylate ligand A, which has an alicyclic structure of a saturated hydrocarbon. From the viewpoint of ease of production by organic synthesis, the alicyclic structure of the saturated hydrocarbon is preferably composed of 3 to 10 carbon atoms, more preferably 3 to 8 carbon atoms, and particularly preferably 3 to 5 carbon atoms. Examples of the alicyclic structure of the saturated hydrocarbon include a cycloalkyl ring.
As the cycloalkyl ring, from the viewpoint of ease of production by organic synthesis, a cycloalkyl ring having 3 to 10 carbon atoms is preferred, a cycloalkyl ring having 3 to 8 carbon atoms is more preferred, a cycloalkyl ring having 3 to 6 carbon atoms is even more preferred, and a cycloalkyl ring having 3 to 5 carbon atoms is particularly preferred. Specifically, any one of a cyclopropane ring, a cyclopentane ring, a cyclobutane ring, a cyclohexane ring, and a norbornane ring is preferred.
From the viewpoints of ease of removal upon exposure and stability in the absence of exposure, the carboxylate ligand A has an alicyclic structure bonded to a carboxylate group, and of the alicyclic structure, carbon _C1 in the alicyclic structure bonded to the carboxylate group is preferably a tertiary or quaternary carbon, most preferably a tertiary carbon. Carbon _C1 in the alicyclic structure bonded to the carboxylate group is preferably one of the carbons constituting the cyclic structure of the alicyclic structure.

Furthermore, the carboxylate ligand A may have one or more substituents R in the alicyclic structure of the saturated hydrocarbon. The substituent R is an organic group or a halogen atom, and such an organic group may contain a halogen atom or a heteroatom. Examples of the organic group include hydrocarbon groups such as alkyl groups and cycloalkyl groups, aromatic groups, ester groups, sulfonyl groups, alkoxy groups, amide groups, amino groups, and carbonyl oxygen groups. The number of carbon atoms in the substituent R is preferably 1 to 10, more preferably 1 to 5, and particularly preferably 1 to 3.
Specific examples of the substituent R include hydrocarbon groups such as linear alkyl groups such as a methyl group and an ethyl group, branched alkyl groups such as an isopropyl group and a butyl group, halogenated alkyl groups such as a halogenated methyl group, a halogenated ethyl group and a halogenated propyl group, and cycloalkyl groups such as a cyclopropyl group and a cyclobutyl group.
Examples of the aromatic group include aryl groups such as a phenyl group and a naphthyl group, arylalkyl groups, and alkylaryl groups.
When the organic group contains a heteroatom, examples of the organic group include an ester group, a sulfonyl group, an alkoxy group, an amide group, an amino group, a carbonyl oxygen group, etc. Examples of the heteroatom include oxygen, nitrogen, phosphorus, sulfur, and silicon.
Examples of the ester group include alkyl ester groups such as an acetyl group, an ethyl ester group, and an n-propyl ester group, and aromatic ester groups such as a phenyl ester group.
Examples of the sulfonyl group include alkylsulfonyl groups such as a methylsulfonyl group, an ethylsulfonyl group, and an n-propylsulfonyl group.
Examples of the alkoxy group include a methoxy group, an ethoxy group, an n-propoxy group, and a phenoxy group.
Examples of amino groups include amino groups ( _-NH2 ), aminoalkyl groups such _{as aminomethyl groups (NH2-CH2-), aminoethyl groups (NH2-C2H4- ) , and aminopropyl} groups ( _{NH2 - C3H6-} ), and dialkylamino groups such as dimethylamino (( _CH3 ) _2N- ) and diethylamino (( _C2H5 ) _2N- ) _.
Examples of the amide group include alkylamide groups such as a methylamide group ((CH ₃ ) ₂ N(C═O)—) and an ethylamide group ((C ₂ H ₅ ) ₂ N(C═O)—).
Also included is a carbonyl oxygen group (C=O).
The substituent R may contain an unsaturated hydrocarbon in its structure.
Examples of halogen atoms include fluorine, chlorine, and bromine.

In terms of film formability, exposure sensitivity, and solvent solubility, the substituent R is preferably a saturated hydrocarbon group, particularly an alkyl group, and more preferably does not contain an unsaturated hydrocarbon or aromatic group in the structure of the substituent R.
This is because, when the carboxylate ligand A is replaced with (meth)acrylic acid, there tends to be room for improvement in terms of film formability. Furthermore, when the carboxylate ligand A of the present cluster compound is replaced with an aromatic carboxylic acid such as benzoic acid, there tends to be room for improvement in terms of exposure sensitivity and solvent solubility. Furthermore, when the carboxylate ligand A of the present cluster compound is replaced with a carboxylate ligand having an alicyclic structure of an unsaturated hydrocarbon, the unsaturated hydrocarbon tends to undergo unintended chain reactions due to radicals generated after exposure, resulting in roughness.
Furthermore, it is most preferable that the carboxylate ligand A does not have a substituent R.

The structure of carboxylate ligand A can be analyzed using known techniques, for example, NMR.

The molecular weight of the present cluster compound is preferably 1000 to 8000, more preferably 1000 to 6000, and particularly preferably 1500 to 5000. If the molecular weight of the present cluster compound is below the above upper limit, the volume is small, and therefore roughness and resolution are expected to be improved, while if the molecular weight is above the above lower limit, coating properties and etching resistance tend to be improved. Note that this molecular weight is a guideline, and is not intended to be limiting, as it does not determine lithography properties by itself.
The molecular weight of the present cluster compound can be analyzed by known techniques, for example, by NMR.

[Manufacturing method]
The present cluster compound can be produced, for example, by reacting in a solution a compound containing a transition metal atom with a carboxylic acid having a structure of carboxylate ligand A. As an example, the present cluster compound can be produced by reacting a solution containing a compound containing a transition metal atom with a carboxylic acid having a structure of carboxylate ligand A.

Examples of compounds containing transition metal atoms include organic compounds containing transition metal atoms, such as metal alkoxides, and specific examples include zirconium normal propoxide, zirconium tertiary butoxide, hafnium normal propoxide, and hafnium tertiary butoxide.

An example of a carboxylic acid having a carboxylate ligand A structure is a carboxylic acid in which a carboxy group is bonded to an alicyclic structure made of saturated hydrocarbon. The carboxylic acid exemplified by the following general formula (1) has an alicyclic structure made of saturated hydrocarbon with six carbon atoms, one of which is bonded to a carboxy group and another to a substituent.

Examples of carboxylic acids having the structure of carboxylate ligand A include carboxylic acids having the structure represented by general formula (1) above, and more specific examples include cyclobutanecarboxylic acid, cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, 2-methyl-1-cyclohexanecarboxylic acid, 3-methyl-1-cyclohexanecarboxylic acid, and 3-oxocyclobutane-1-carboxylic acid.

To explain the production method in more detail, a solution containing a compound containing a transition metal atom and a carboxylic acid having a carboxylate ligand A structure are placed in a reaction vessel and stirred. A solvent may be added to dissolve the raw materials.

The reaction temperature is preferably room temperature to 150°C, more preferably room temperature to 120°C, from the viewpoint of completing the reaction and avoiding undesirable side reactions. The reaction time is preferably 1 to 100 hours, more preferably 1 to 24 hours. In the present invention, room temperature refers to approximately 1°C to 30°C.

If the product precipitates or crystallizes after the reaction, the cluster compound can be obtained by filtering it. Note that the solution after the reaction may be cooled to -30°C to 20°C in order to obtain the precipitate or crystallize the product.
If no precipitation of the product is observed after the reaction, the target product can be recovered by distilling off the solvent by applying a reduced pressure to the reaction vessel, or by contacting the reaction solution with a poor solvent to reprecipitate the product.

The reaction vessel is preferably a sealed vessel, and for small volumes, a Schlenk tube or the like can be used, and the reaction is preferably carried out under a nitrogen or argon atmosphere.
The reaction vessel is preferably a flask equipped with a reflux condenser, and when heating, the reaction is preferably carried out in a nitrogen or argon atmosphere.

The solution containing the compound containing a transition metal atom and the carboxylic acid having a carboxylate ligand A structure are preferably mixed in a ratio of 1:2 to 1:4, more preferably 1:4, by weight of the substances.

[Photosensitive composition]
A photosensitive composition according to one embodiment of the present invention (hereinafter also referred to as the present photosensitive composition) contains the present cluster compound. The present photosensitive composition may contain only one type of the present cluster compound, or may contain two or more types of the present cluster compound.
The content of the cluster compound in the photosensitive composition is 50 to 100% by mass, preferably 60 to 100% by mass, and particularly preferably 70 to 90% by mass, of the total solids of the photosensitive composition. The total solids refer to solids obtained by evaporating the photosensitive composition to dryness by evaporation or the like.
The concentration of the cluster compound in the photosensitive composition is preferably 0.1% by mass or more and 70% by mass or less, more preferably 0.5% by mass or more and 50% by mass or less, and particularly preferably 1% by mass or more and 40% by mass or less.
When the content of the present cluster compound in the present photosensitive composition is equal to or greater than the above lower limit, good exposure sensitivity can be obtained.

[Photoacid generator]
The photosensitive composition can also function by containing, together with the cluster compound, a photoacid generator that generates an acid upon the action of actinic radiation.
Examples of actinic radiation include the bright line spectrum of a mercury lamp, far ultraviolet light represented by an excimer laser, extreme ultraviolet light (EUV light), X-rays, and electron beams. From the viewpoint of resolution, a shorter exposure wavelength is preferred, and extreme ultraviolet light (EUV light) emitting light with a wavelength of 6 nm or more and 15 nm or less is preferred.

Such photoacid generators that generate acid upon exposure to actinic radiation are not particularly limited as long as they are well known, but compounds that generate organic acids, such as sulfonic acid, bis(alkylsulfonyl)imide, and/or tris(alkylsulfonyl)methide upon exposure to actinic radiation, are preferred.

The photoacid generators can be used singly or in combination of two or more. When two or more types are used in combination, preferred embodiments include (1) using two photoacid generators with different acid strengths in combination, and (2) using two photoacid generators with different sizes (molecular weight or number of carbon atoms) of the acid they generate in combination.

Examples of (1) include the combined use of a fluorine-containing sulfonic acid generator and a tris(fluoroalkylsulfonyl)methide acid generator, the combined use of a fluorine-containing sulfonic acid generator and a non-fluorine-containing sulfonic acid generator, and the combined use of an alkylsulfonic acid generator and an arylsulfonic acid generator.

An example of embodiment (2) is the combined use of two acid generators whose generated acid anions differ in the number of carbon atoms by four or more.

The photosensitive composition is preferably a photosensitive composition for use with actinic radiation, and a photosensitive composition that reacts with actinic radiation is preferred because the development speed in the developer changes, allowing a pattern to be formed after a certain period of development. Examples of actinic radiation include the bright line spectrum of a mercury lamp, far ultraviolet light typified by excimer lasers, extreme ultraviolet light (EUV light), X-rays, and electron beams.

The actinic radiation preferably has a shorter wavelength because higher resolution can be obtained, and preferably has a wavelength of 6 nm or more and 15 nm or less, more preferably 6.5 nm or less and 13.5 nm or less. In other words, extreme ultraviolet (EUV) light is preferred.
In other words, the present photosensitive composition is preferably a photosensitive composition that reacts with actinic radiation having a wavelength of 6 nm or more and 15 nm or less. The reaction means that the photosensitive composition absorbs the irradiated actinic radiation and is modified by active species such as radicals and ions that are generated.

The present cluster compound will react with light even when used alone in a photosensitive composition. When a photoacid generator is added, it acts synergistically with the present cluster compound in the photosensitive composition to increase the photosensitivity of the present cluster compound. Therefore, if a photosensitive composition composed only of the present cluster compound does not have sufficient photosensitivity to meet the required specifications, it is preferable to add a photoacid generator.

When the photosensitive composition contains a photoacid generator, the content of the photoacid generator in the photosensitive composition (the total amount when multiple photoacid generators are used) is preferably 0.1 to 30% by mass, more preferably 0.5 to 20% by mass, and even more preferably 1 to 15% by mass, based on the total of the components of the photosensitive composition other than the solvent.

If the content of the photoacid generator in the photosensitive composition is above the above-mentioned lower limit, the effect of increasing photosensitivity can be obtained, and if it is below the above-mentioned upper limit, the composition is less affected by the poor film-forming properties of the photoacid generator, and therefore good film-forming properties based on the photosensitive compound of the present invention can be obtained, which is preferable.

[solvent]
The photosensitive composition generally contains a solvent for preparing the composition.
The solvent for preparing the photosensitive composition is not particularly limited as long as it dissolves each component, and examples thereof include toluene, alkylene glycol monoalkyl ether carboxylates (such as propylene glycol monomethyl ether acetate (PGMEA; 1-methoxy-2-acetoxypropane)), alkylene glycol monoalkyl ethers (such as propylene glycol monomethyl ether (PGME; 1-methoxy-2-propanol)), alkyl lactate esters (such as ethyl lactate and methyl lactate), cyclic lactones (such as γ-butyrolactone, preferably having 4 to 10 carbon atoms), linear or cyclic ketones (such as 2-heptanone and cyclohexanone, preferably having 4 to 10 carbon atoms), alkylene carbonates (such as ethylene carbonate and propylene carbonate), alkyl carboxylates (preferably alkyl acetates such as butyl acetate), alkyl alkoxyacetates (ethyl ethoxypropionate), alkylamides (N,N-dimethylformamide), and alkyl sulfoxides (dimethyl sulfoxide). Other usable solvents include, for example, the solvents described in paragraphs [0244] and after of US Patent Application Publication No. 2008/0248425A1.

Of the above, toluene, PGMEA, ethyl lactate, cyclohexanone, 2-heptanone, N,N-dimethylformamide, dimethyl sulfoxide, alkylene glycol monoalkyl ether carboxylate and alkylene glycol monoalkyl ether are preferred.
These solvents may be used alone or in combination of two or more. When two or more solvents are used in combination, it is preferable to mix a solvent having a hydroxyl group with a solvent not having a hydroxyl group.

As a solvent having a hydroxyl group, alkylene glycol monoalkyl ether is preferred, and as a solvent not having a hydroxyl group, alkylene glycol monoalkyl ether carboxylate, N,N-dimethylformamide, and dimethyl sulfoxide are preferred.

The solvent for the present photosensitive composition preferably has a solubility parameter (SP value) of 7.5 to 11, more preferably 8 to 11. The solubility parameter (SP value) will be described later.
The content of the solvent in the total amount of the photosensitive composition can be adjusted as appropriate depending on the film thickness of the pattern to be formed, etc., but is generally adjusted so that the total concentration of components other than the solvent in the photosensitive composition is 0.5 to 30 mass %, preferably 1.0 to 20 mass %, more preferably 1.5 to 10 mass %, and particularly preferably 1.5 to 5 mass %.

[Surfactant]
The photosensitive composition preferably further contains a surfactant, preferably a fluorine-based and/or silicone-based surfactant.
Examples of surfactants that fall into this category include Megafac F176 and Megafac R08 manufactured by Dainippon Ink and Chemicals, Inc., PF656 and PF6320 manufactured by OMNOVA, Troisol S-366 manufactured by Troy Chemical Co., Ltd., Fluorad FC430 manufactured by Sumitomo 3M Limited, and Polysiloxane Polymer KP-341 manufactured by Shin-Etsu Chemical Co., Ltd.

Furthermore, surfactants other than fluorine-based and/or silicone-based surfactants can also be used, more specifically, polyoxyethylene alkyl ethers, polyoxyethylene alkylaryl ethers, etc.
Other known surfactants may also be used as appropriate, such as those described in U.S. Patent Application Publication No. 2008/0248425A1, paragraphs [0273] and thereafter.
The surfactants may be used alone or in combination of two or more kinds.
The content of the surfactant is preferably from 0.0001 to 2% by mass, more preferably from 0.001 to 1% by mass, based on the total amount of components other than the solvent in the photosensitive composition.

[resin]
Although the present photosensitive composition can be used alone to form a pattern, it may also contain a resin material in addition to the present cluster compound. The resin material is not particularly limited as long as it is soluble in a solvent, and examples thereof include novolac resin, styrene resin, and acrylic resin. These resins may contain one or more copolymers.

These resins may be used alone or in combination of two or more, and may contain dissolution-inhibiting groups that decompose in the presence of chemically active species such as acids or radicals, or crosslinking groups that crosslink. Examples of dissolution-inhibiting groups that decompose in the presence of chemically active species such as acids or radicals include alkoxycarbonyl groups and acetal groups. Examples of crosslinking groups that crosslink in the presence of chemically active species such as acids or radicals include vinyl groups, carbodiimide groups, N-hydroxyester groups, imide ester groups, maleimide groups, haloacetyl groups, pyridyl disulfide groups, hydrazide groups, alkoxyamino groups, and diazirine groups.

[Other additives]
In addition to the components described above, the photosensitive composition may contain, as appropriate, carboxylic acids, carboxylic acid onium salts, dissolution-inhibiting compounds having a molecular weight of 3,000 or less as described in, for example, Proceedings of SPIE, 2724, 355 (1996), dyes, plasticizers, photosensitizers, light absorbers, crosslinking agents, antioxidants, and the like.
In particular, carboxylic acids are preferably used to improve performance, and aromatic carboxylic acids such as benzoic acid and naphthoic acid are preferred.
The content of the carboxylic acid is preferably from 0.01 to 10% by mass, more preferably from 0.01 to 5% by mass, and even more preferably from 0.01 to 3% by mass, based on the total amount of components other than the solvent in the photosensitive composition.

[Method for producing the present photosensitive composition]
The photosensitive composition can be produced by dissolving the cluster compound, a photoacid generator (if used) and other components in a solvent for preparation, and filtering the solution as needed. The filter is preferably made of polytetrafluoroethylene, polyethylene, or nylon with a pore size of 0.2 μm or less, more preferably 0.1 μm or less, and even more preferably 0.05 μm or less.

[Pattern Forming Method]
A pattern formation method according to one embodiment of the present invention (hereinafter also referred to as the present pattern formation method) includes the steps of applying the present photosensitive composition to a substrate, exposing the applied photosensitive composition to actinic radiation, and developing the exposed photosensitive composition.
More specifically, the method includes a step of applying the present photosensitive composition onto a substrate to form a photosensitive layer, a step of irradiating predetermined regions of the photosensitive layer with actinic radiation to perform pattern exposure, and a step of developing the exposed photosensitive layer to selectively remove exposed or unexposed areas of the photosensitive layer.
The step of forming the photosensitive layer provides a substrate having a photosensitive layer, the step of pattern exposure provides a substrate having a photosensitive layer with a latent image, and the step of development provides a substrate having a patterned layer.

[Photosensitive layer formation process]
The photosensitive layer can be formed by applying the photosensitive composition to a substrate (e.g., silicon, silicon dioxide coated) such as those used in the manufacture of integrated circuit elements by a suitable application method such as a spinner, and then drying at 50 to 150°C.
In this case, if necessary, a commercially available inorganic or organic anti-reflective coating can be used, and further, an anti-reflective coating can be applied to the lower layer of the resist.

[Exposure process]
In the present invention, unless otherwise specified, "exposure to actinic radiation" includes not only exposure to far ultraviolet light represented by a mercury lamp or an excimer laser, X-rays, extreme ultraviolet light (EUV light), and the like, but also exposure to writing using particle beams such as electron beams and ion beams.
The exposure can be carried out by irradiating predetermined areas of the formed photosensitive layer with actinic radiation through a predetermined mask to perform pattern exposure, or by irradiating the layer with an electron beam to perform pattern exposure by drawing (direct drawing) without using a mask.
The actinic radiation is not particularly limited, but examples thereof include KrF excimer laser, ArF excimer laser, extreme ultraviolet radiation (EUV light), and electron beams. Of these, extreme ultraviolet radiation (EUV light) and electron beams are preferred, and as described above, extreme ultraviolet radiation (EUV light) that emits actinic radiation with a wavelength of 6 nm to 15 nm is preferred.

After the exposure, baking (heating) may or may not be performed before development.
When baking (heating) is performed, the heating temperature is preferably 50 to 200°C, more preferably 60 to 180°C, and even more preferably 80 to 150°C.
When baking (heating) is performed, the heating time is preferably from 30 to 300 seconds, more preferably from 30 to 180 seconds, and even more preferably from 30 to 90 seconds.
Heating can be carried out by means of a conventional exposure/development device, and may also be carried out using a hot plate or the like.

[Development process]
After the exposure, development is carried out to selectively remove the exposed or unexposed areas of the photosensitive layer. As the development method, a known method can be adopted, for example, a method using a gas or a method using a developer.

<Developer>
As the developer, an organic solvent is preferably used, preferably one having a vapor pressure of 5 kPa or less at 20° C., more preferably 3 kPa or less, and particularly preferably 2 kPa or less. By setting the vapor pressure of the organic solvent to 5 kPa or less, evaporation of the developer on the substrate or in the developing cup is suppressed, improving the temperature uniformity within the surface of the pattern-formed substrate, and as a result, improving the dimensional uniformity within the surface of the pattern-formed substrate.

A variety of organic solvents can be used as the developer, including at least one solvent selected from the group consisting of ester solvents, ketone solvents, alcohol solvents, amide solvents, sulfoxide solvents, ether solvents, and hydrocarbon solvents.

Examples of ester-based solvents include alkyl carboxylate solvents such as methyl acetate, butyl acetate, ethyl acetate, isopropyl acetate, amyl acetate, ethyl-3-ethoxypropionate, propylene glycol diacetate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, methyl formate, ethyl formate, butyl formate, propyl formate, ethyl lactate, butyl lactate, and propyl lactate; and alkylene glycol monoalkyl ether carboxylate solvents such as propylene glycol monomethyl ether acetate (PGMEA; also known as 1-methoxy-2-acetoxypropane), ethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, and propylene glycol monoethyl ether acetate. Butyl acetate, amyl acetate, ethyl lactate, and propylene glycol monomethyl ether acetate are more preferred.

Ketone solvents include, for example, 1-octanone, 2-octanone, 1-nonanone, 2-nonanone, acetone, 4-heptanone, 1-hexanone, 2-hexanone, diisobutyl ketone, cyclopentanone, cyclohexanone, methylcyclohexanone, phenylacetone, methyl ethyl ketone, methyl amyl ketone, methyl isobutyl ketone, acetylacetone, acetonylacetone, ionone, diacetonyl alcohol, acetylcarbinol, acetophenone, methyl naphthyl ketone, isophorone, and propylene carbonate. Alkyl ketone solvents, such as methyl isobutyl ketone, methyl amyl ketone, cyclopentanone, cyclohexanone, and 2-heptanone, are more preferred.

Examples of alcohol-based solvents include methyl alcohol, ethyl alcohol, n-propyl alcohol including 1-propanol or 2-propanol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, isobutyl alcohol, hexyl alcohol such as n-hexyl alcohol, heptyl alcohol such as n-heptyl alcohol, octyl alcohol such as n-octyl alcohol, and n-decanol; and glycols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, and 1,4-butylene glycol. Examples of suitable solvents include alkylene glycol monoalkyl ether solvents such as ethylene glycol monomethyl ether, propylene glycol monomethyl ether (PGME; also known as 1-methoxy-2-propanol), ethylene glycol monoethyl ether, propylene glycol monoethyl ether, diethylene glycol monomethyl ether, and triethylene glycol monoethyl ether; glycol ether solvents such as methoxymethylbutanol and propylene glycol dimethyl ether; and phenolic solvents such as phenol and cresol, with 1-hexanol, 2-hexanol, 1-octanol, 2-ethylhexanol, propylene glycol monomethyl ether, and cresol being more preferred.
Examples of amide solvents that can be used include N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, hexamethylphosphoric triamide, and 1,3-dimethyl-2-imidazolidinone.

As a sulfoxide solvent, for example, dimethyl sulfoxide can be used.

Examples of ether-based solvents include the alkylene glycol monoalkyl ether-based solvents and glycol ether-based solvents mentioned above, as well as dioxane, tetrahydrofuran, tetrahydropyran, etc.

Examples of hydrocarbon solvents include aromatic hydrocarbon solvents such as toluene and xylene, and aliphatic hydrocarbon solvents such as pentane, hexane, octane, decane, and dodecane.

The developer preferably contains one or more solvents selected from alkylene glycol monoalkyl ether carboxylate solvents, alkylene glycol monoalkyl ether solvents, alkyl carboxylate solvents, and alkyl ketone solvents, and more preferably contains one or more solvents selected from dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, ethylene glycol, methyl alcohol, ethyl alcohol, 1-propanol, and 2-propanol.

It is preferable to use a developer containing at least one organic solvent selected from the group consisting of ester solvents that do not have a hydroxyl group in the molecule, ketone solvents that do not have a hydroxyl group in the molecule, and ether solvents, amide solvents, and sulfoxide solvents that do not have a hydroxyl group in the molecule.

The organic solvent used as the developer in the present invention is preferably an organic solvent with a solubility parameter (SP value) of 7.5 or more and 11 or less. Organic solvents with a solubility parameter of 7.5 or more will increase the development rate of the dissolved area, while organic solvents with a solubility parameter of 11 or less are preferred because they can suppress the development rate of the pattern formation area. It is more preferable that the solubility parameter of the organic solvent in the developer is 8 or more and 11 or less.

In the present invention, the solubility parameter (SP value) is calculated using the method proposed by Fedors et al. Specifically, the value is determined by referring to "POLYMER ENGINEERING AND SCIENCE, FEBRUARY, 1974, Vol. 14, No. 2, ROBERT F. FEDORS. (P. 147-154)." The SP value is a physical property determined by the content of hydrophobic and hydrophilic groups in the molecule, and when a mixed solvent is used, it refers to the value for the mixture.

Examples of organic solvents that satisfy the above SP values include diethylene glycol monomethyl ether (SP value = 10.7), triethylene glycol monomethyl ether (SP value = 10.7), ethylene glycol monoisopropyl ether (SP value = 10.9), ethylene glycol monobutyl ether (SP value = 10.2), diethylene glycol monobutyl ether (SP value = 10.0), triethylene glycol monobutyl ether (SP value = 10.0), ethylene glycol monoisobutyl ether (SP value = 9.1), ethylene glycol monohexyl ether (SP value = 9.9), diethylene glycol monohexyl ether (SP value = 9.7), diethylene glycol mono-2-ethylhexyl ether (SP value = 9.3), ethylene glycol monoallyl ether (SP value = 10.8), ethylene glycol monophenyl ether (SP value = 10.8), ethylene glycol monobenzyl ether (SP value = 10.9), propylene glycol monomethyl ether (SP value = 10.0), dipropylene glycol Cholesterol monomethyl ether (SP value = 9.7), tripropylene glycol monomethyl ether (SP value = 9.4), propylene glycol monopropyl ether (SP value = 9.6), dipropylene glycol monopropyl ether (SP value = 9.8), propylene glycol monobutyl ether (SP value = 9.0), dipropylene glycol monobutyl ether (SP value = 9.6), ethylene glycol monomethyl ether acetate (SP value = 10.0), ethylene glycol monoethyl ether acetate (SP value = 9.6), ethylene glycol monobutyl ether acetate (SP value = 8.9), diethylene glycol monoethyl ether acetate (SP value = 9.4), diethylene glycol monobutyl ether acetate (SP value = 9.0), propylene glycol monomethyl ether acetate (SP value = 9.4), propylene glycol monoethyl ether acetate (SP value = 9.0), dipropylene glycol monomethyl ether acetate (SP value = 9.2), and the like.
The organic solvents described above may be used in combination, or may be used in combination with other solvents or water. For example, as described in International Publication No. 2020/210660, it is also possible to use a developer composition that contains at least two solvents, each independently containing at least 55% by volume of one or more solvents having a Hansen solubility parameter δH + δP of at most about 16 (J/cm ³ ) 1/2 , and about 0.25% to about 45% by volume of one or more solvents each independently containing at least about 16 (J/cm ³ ) 1/2 .

The concentration of the above organic solvents (total concentration if multiple organic solvents are mixed) in the developer is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more. It is particularly preferable for the developer to consist essentially of organic solvents. Note that "consisting essentially of organic solvents" includes cases where trace amounts of surfactants, antioxidants, stabilizers, antifoaming agents, etc. are contained.

The water content in the developer is preferably 10% by weight or less, more preferably 5% by weight or less, particularly preferably 3% by weight or less, and most preferably substantially no water. By keeping the water content at 10% by weight or less, good development characteristics can be obtained.

If necessary, a suitable amount of a surfactant may be added to the developer used in the present invention.
As the surfactant, the same surfactants as those used in the photosensitive composition of the present invention can be used.
The amount of the surfactant used is usually from 0.001 to 5% by weight, preferably from 0.005 to 2% by weight, and more preferably from 0.01 to 0.5% by weight, based on the total amount of the developer.

<Developing method>
Examples of development methods that can be applied include a method of immersing a substrate in a tank filled with a developer for a certain period of time (dip method), a method of developing by piling up a developer on the surface of the substrate by surface tension and leaving it to stand for a certain period of time (puddle method), a method of spraying the developer onto the surface of the substrate (spray method), and a method of continuously dispensing the developer while scanning a developer dispensing nozzle at a constant speed over a substrate that is rotating at a constant speed (dynamic dispense method).

After the development step, a step of stopping the development while replacing the solvent with another solvent may be carried out.
The development time is preferably a time required for the cluster compound and the like in the unexposed or exposed areas of the photosensitive layer to be sufficiently dissolved, and is usually preferably 10 to 300 seconds, more preferably 20 to 120 seconds.
The temperature of the developer is preferably from 0 to 50°C, more preferably from 15 to 35°C.
The amount of developer can be adjusted appropriately depending on the development method.

[Rinse process]
The present pattern forming method may include, after the development step, a step of washing with a rinse liquid containing an organic solvent.

<Rinse>
The organic solvent used in the rinse liquid preferably has a vapor pressure of 0.05 kPa or more and 5 kPa or less, more preferably 0.1 kPa or more and 5 kPa or less, and most preferably 0.12 kPa or more and 3 kPa or less at 20° C. By adjusting the vapor pressure of the organic solvent used in the rinse liquid to 0.05 kPa or more and 5 kPa or less, the temperature uniformity within the wafer surface is improved, and further, swelling due to penetration of the rinse liquid is suppressed, thereby improving the dimensional uniformity within the wafer surface.

Various organic solvents can be used as the rinse solution, but for the present cluster compound, it is preferable to use a rinse solution containing at least one organic solvent selected from hydrocarbon solvents, ketone solvents, ester solvents, alcohol solvents, amide solvents, and ether solvents, or water.
More preferably, after development, a step of cleaning is performed using a rinse solution containing at least one organic solvent selected from ketone solvents, ester solvents, alcohol solvents, amide solvents, and hydrocarbon solvents. Even more preferably, after development, a step of cleaning is performed using a rinse solution containing at least one organic solvent selected from the group consisting of alcohol solvents and hydrocarbon solvents. For example, as described in International Publication No. 2020/081483, a method in which the rinse solution contains a quaternary ammonium hydroxide aqueous solution and the developer solution contains an organic solvent can be used, or a method in which the developer solution contains a quaternary ammonium hydroxide aqueous solution and the rinse solution contains an organic solvent can be used.

Specific examples of the ketone-based solvents, ester-based solvents, alcohol-based solvents, amide-based solvents, ether-based solvents and hydrocarbon-based solvents used as the rinse liquid are the same as those explained above for the developer.
It is particularly preferable to use a rinse solution containing at least one organic solvent selected from the group consisting of monohydric alcohol solvents, hydrocarbon solvents, and amide solvents.

The monohydric alcohol solvent used in the rinsing step after development includes linear, branched, and cyclic monohydric alcohols. Specific examples include 1-butanol, 2-butanol, 3-methyl-1-butanol, tert-butyl alcohol, isopropyl alcohol, cyclopentanol, and cyclohexanol. 1-butanol, 2-butanol, 3-methyl-1-butanol, and isopropyl alcohol are preferred.

Examples of hydrocarbon solvents include aromatic hydrocarbon solvents such as toluene and xylene, and aliphatic hydrocarbon solvents such as octane, decane, and dodecane.
As the amide solvent, N,N-dimethylformamide or the like can be used.
The above-mentioned components may be mixed in plural, or may be mixed with an organic solvent other than those mentioned above.

The above organic solvents may be mixed with water, but the water content in the rinse solution is usually 30% by weight or less, preferably 10% by weight or less, more preferably 5% by weight or less, and particularly preferably 3% by weight or less. It is most preferable that the rinse solution does not contain water. By keeping the water content at 30% by weight or less, good development characteristics can be obtained.

The rinse solution may contain an appropriate amount of a surfactant.
As the surfactant, the same surfactants as those used in the photosensitive composition described above can be used, and the amount used is usually 0.001 to 5 mass %, preferably 0.005 to 2 mass %, and more preferably 0.01 to 0.5 mass %, based on the total amount of the rinse solution.

<Rinse method>
In the rinsing step, the developed pattern-formed substrate is washed with a rinsing liquid containing the organic solvent.
The cleaning method is not particularly limited, but may be, for example, a method in which a rinse solution is continuously applied to a substrate rotating at a constant speed (spin coating method), a method in which a substrate is immersed in a tank filled with rinse solution for a certain period of time (dip method), or a method in which a rinse solution is sprayed onto the substrate surface (spray method). Among these, it is preferable to perform the cleaning process using the spin coating method, and then rotate the substrate at a rotation speed of 2000 to 4000 rpm after cleaning to remove the rinse solution from the substrate. The rotation time of the substrate can be set depending on the rotation speed within a range that achieves removal of the rinse solution from the substrate, but is usually 10 seconds to 3 minutes. Rinsing is preferably performed at room temperature.

The rinsing time is preferably set so that the developing solvent does not remain on the substrate, and is usually preferably 10 to 300 seconds, more preferably 20 to 120 seconds.
The temperature of the rinse solution is preferably 0 to 50°C, more preferably 15 to 35°C.
The amount of the rinse solution can be adjusted appropriately depending on the rinse method.

[Post-processing process]
After the development treatment or the rinsing treatment, a treatment can be carried out in which the developer or the rinsing liquid adhering to the pattern is removed using a supercritical fluid.
Furthermore, after the development treatment, rinsing treatment, or treatment with a supercritical fluid, a heat treatment can be carried out to remove the solvent remaining in the pattern. The heating temperature and time are not particularly limited as long as a good resist pattern can be obtained, but are usually 40 to 160°C and 10 seconds to 3 minutes. The heat treatment may be carried out multiple times.

[Application]
The photosensitive composition and the pattern forming method are suitable for use in the production of semiconductor microcircuits, such as those used in the production of VLSIs and high-capacity microchips, and can produce substrates having patterned layers. During the production of semiconductor microcircuits, the resist film on which the pattern has been formed is subjected to circuit formation and etching, and the remaining resist film portion is then finally removed with a solvent or the like.

Below, one example of the present invention will be described. However, the present invention is not limited to this example. In the example, "parts" and "%" are by mass unless otherwise specified.

The following compounds 1 to 3 were prepared to obtain Examples 1 to 3. The composition and ligand structure of each compound were measured by ¹ H-NMR.

<Compound 1>
A 100 mL recovery flask was charged with 10 g of zirconium (IV) tetrapropoxide (70% 1-propanol solution, manufactured by Tokyo Chemical Industry Co., Ltd.), 10.1 g of cyclohexanecarboxylic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), and 20 mL of hexane, and the mixture was stirred at 90°C for 1 hour. The mixture was then cooled to room temperature, and 150 mL of methanol was added. The mixture was concentrated under reduced pressure until approximately 90% of the solvent was removed, resulting in the precipitation of a solid. The supernatant was decanted, and the solid was washed twice with 100 mL of methanol and then dried, yielding 5.0 g of compound 2 as a white solid.
¹ H-NMR (CDCl ₃ ) δ2.5~1.0 (highly broadnend peak)

<Compound 2>
A 500 mL recovery flask was charged with 50 g of zirconium (IV) tetrapropoxide (70% 1-propanol solution, manufactured by Tokyo Chemical Industry Co., Ltd.), 64.1 g of cyclobutanecarboxylic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), and 50 mL of toluene, and the mixture was stirred at 100° C. for 4 hours. The mixture was then cooled to room temperature, concentrated under reduced pressure, and a small amount of acetonitrile was added, followed by cooling to below 0° C., yielding 18.6 g of precipitated compound 2 as a white solid.
¹ H-NMR (CDCl ₃ ) δ3.19-2.88 (12H, m), 2.37-1.75 (72H, m)
ESI-MS (negative): Cluster-derived peaks at m/z 1741-1875

<Compound 3>
5 g of zirconium (IV) tetrapropoxide (70% 1-propanol solution, manufactured by Tokyo Chemical Industry Co., Ltd.), 7.32 g of cyclopentanecarboxylic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), and 11.5 mL of toluene were placed in a 100 mL recovery flask and stirred at 100° C. for 6 hours. The mixture was then cooled to 0° C. or below, and 2.3 g of precipitated compound 3 was obtained as a white solid.
¹ H-NMR (CDCl ₃ ) δ2.87~2.57 (6H, m), 2.01~1.50 (96H, m)
ESI-MS (negative): Cluster-derived peaks at m/z 1700-2200

<Preparation of Photosensitive Composition (Resist Solution)>
The above compounds 1 to 3 were each dissolved in 2-heptanone at a concentration of 5% by mass, and the solution was filtered through a 0.2 μm filter to obtain a resist solution.

<Resist film formation and pattern writing>
The prepared resist solution was applied to a patterned substrate (silicon wafer) by spin coating to form a resist film with a thickness of approximately 40 nm. The resulting resist film was baked at 90°C for 90 seconds, and then patterned using an electron beam lithography system (electron beam acceleration voltage: 100 keV).

<Developing>
After pattern writing, Compound 1 was developed with 2-methyl-2-pentanol (25°C, 30 seconds), and Compounds 2 and 3 were developed with 2-heptanone (25°C, 30 seconds) to obtain negative patterns, which were designated Examples 1 to 3, respectively.

<Sensitivity measurement>
Extreme ultraviolet (EUV) exposure was performed at different doses, and the film thickness of the developed pattern was measured using a contact profilometer. The EUV exposure dose at which the amount of change in film thickness was maximized was determined as an index of sensitivity. Note that sensitivity is higher when the exposure dose (unit: mJ/ ^cm2 ) is low and lower when the exposure dose is high.
The results are shown in Table 1.

[Comparative Example 1]
Polystyrene (PS, weight average molecular weight 4000) manufactured by Aldrich was dissolved in propylene glycol monomethyl ether acetate at a concentration of 2% by mass and filtered through a 0.2 μm filter to prepare a resist solution. After pattern writing, the PS was developed with propylene glycol monomethyl ether acetate (25°C, 60 seconds) to obtain a negative pattern, which was designated Comparative Example 1.

The resist solution of Comparative Example 1 was evaluated in the same manner as in Examples 1 to 3, and the results are shown in Table 1.

The results in Table 1 confirm that, compared to Comparative Example 1, Examples 1 to 3 have a smaller EUV irradiation dose when the film thickness change is at its maximum, resulting in higher sensitivity.

<Resolution evaluation>
The resolution of Examples 1 to 3 was evaluated using an electron beam lithography device. Line and space (line:space=1:1) patterns with hp (half pitch) of 100 nm, 50 nm, and 30 nm were drawn, developed, and each pattern was observed under a scanning electron microscope to evaluate the drawn patterns. A rating of "A" was given when a line and space pattern was confirmed, a rating of "B" was given when a pattern was confirmed but partially crosslinked, and a rating of "C" was given when no pattern was confirmed.
The results are shown in Table 2.

[result]
From the results of an electron beam (EB) writing test, Examples 1 to 3 were able to form a half-pitch (hp) 100 nm, 50 nm line and space (L&S) pattern (1:1), and in particular, Examples 2 and 3 were able to form a hp 30 mm line and space (L&S) pattern (1:1). Furthermore, as shown in Table 1, it was confirmed that the samples had very high sensitivity to EUV exposure.

These results demonstrate that transition metal cluster compounds composed of a carboxylate ligand with an alicyclic structure of a saturated hydrocarbon and a transition metal element are relatively easy to synthesize, have high sensitivity to EUV, high throughput, are suitable for mass production, and have high resolution, making them highly practical as photoresists capable of forming ultra-fine patterns.

Claims (19)

A transition metal cluster compound containing a transition metal atom and a carboxylate ligand A having an alicyclic structure of a saturated hydrocarbon. The transition metal cluster compound according to claim 1, wherein the carboxylate ligand A comprises an alicyclic structure of a saturated hydrocarbon having at least one substituent R, and the substituent R is an organic group or a halogen atom. The transition metal cluster compound according to claim 1, wherein the alicyclic structure of the carboxylate ligand A has 3 to 10 carbon atoms. The transition metal cluster compound described in claim 1, wherein the transition metal atoms are composed of 2 to 20 atoms. The transition metal cluster compound according to claim 1, wherein the transition metal atom is titanium, hafnium, or zirconium. The transition metal cluster compound according to claim 1, wherein the alicyclic structure of the carboxylate ligand A is a cyclopropane ring, a cyclopentane ring, a cyclobutane ring, a cyclohexane ring, or a norbornane ring. The transition metal cluster compound according to claim ₁ , characterized in that the carbon C1 in the alicyclic structure to which the carboxylate group of the carboxylate ligand A is bonded is a tertiary or quaternary carbon and is one of the carbons constituting the cyclic structure of the alicyclic structure. The transition metal cluster compound according to claim 2, wherein the substituent R is an organic group having 1 to 10 carbon atoms. The transition metal cluster compound according to claim 2, wherein the organic group is any one of a hydrocarbon group, an aromatic group, an ester group, a sulfonyl group, an alkoxy group, an amide group, an amino group, and a carbonyl oxygen group. The transition metal cluster compound according to claim 2, wherein the structure of the substituent R does not contain an unsaturated hydrocarbon or aromatic group. A method for producing a transition metal cluster compound according to any one of claims 1 to 10, comprising reacting a compound containing a transition metal atom with a carboxylic acid having a carboxylate ligand A structure in a solution. A photosensitive composition containing the transition metal cluster compound described in any one of claims 1 to 10. The photosensitive composition according to claim 12, further comprising a solvent. A photosensitive composition comprising the transition metal cluster compound according to any one of claims 1 to 10 in a concentration of 50 to 100 mass % of the total solids. The photosensitive composition according to claim 12, characterized in that it reacts with actinic radiation having a wavelength of 6 nm or more and 15 nm or less. A pattern forming method comprising the steps of: applying the photosensitive composition according to claim 12 to a substrate; exposing the photosensitive composition applied to the substrate to actinic radiation; and developing the exposed photosensitive composition. The pattern formation method according to claim 16, wherein the development is carried out using a developer, and the developer is an organic solvent having a solubility parameter (SP value) of 7.5 or more and 11 or less. A substrate having a patterned layer obtained by the pattern forming method described in claim 16. A method for manufacturing a substrate in which a pattern layer is formed by the pattern formation method described in claim 16.